The present invention relates to improved apparatus and methods for performing qualitative and quantitative analysis of microscopic biological specimens. In particular, the invention relates to such apparatus and methods for isolating, collecting, immobilizing, and/or analyzing microscopic biological specimens or substances which are susceptible to immunospecific or non-specific binding with magnetic-responsive particles having a binding agent for producing magnetically-labeled species within a fluid medium. As used herein, terms such as “magnetically-labeled specimen” shall refer to such biological specimens or substances of investigational interest which are susceptible to such magnetic labeling.
U.S. Pat. No. 5,985,153 describes an apparatus and method wherein an external magnetic gradient is employed to attract magnetically labeled target specimens present in a collection chamber to one of its surfaces, and where an internal magnetic gradient is employed to obtain precise alignment of those specimens on that surface. The movement of magnetically labeled biological specimens to the collection surface is obtained by applying a vertical magnetic gradient to move the magnetically labeled biological specimens to the collection surface. The collection surface is provided with a ferromagnetic capture structure, such as plurality of ferromagnetic lines supported on an optically transparent (viewing) face of a sample chamber.
Once the magnetically labeled biological specimens are pulled sufficiently close to the surface by the externally applied gradient, they come under the influence of an intense local gradient produced by the ferromagnetic collection structure and are immobilized at positions laterally adjacent thereto. The local gradient preferably exceeds adhesion forces which can hold the biological specimens to the transparent surface after they collide with the surface. Alternatively, the adhesiveness of the surface must be sufficiently weak to allow the horizontal magnetic force to move the magnetically labeled biological specimens towards the ferromagnetic structures. The smoothness and the hydrophobic or hydrophilic nature of the surface are factors that can influence the material chosen for the collection surface or the treatment of this surface to obtain a slippery surface.
U.S. Ser. No. 10/733,829 and U.S. Pat. No. 6,790,366 describe methods and apparatus for separating, immobilizing, and quantifying biological substances in a fluid sample, incorporating the principles of the externally applied gradient described above, and further incorporate a high internal gradient magnetic capture structure on the transparent collection wall. The capture structure encourages a uniform alignment of captured biological substances for quantitative analysis with automated enumeration techniques.
U.S. Ser. No. 11/447,562 describe small V-shaped grooves on the fluid side of the optically transparent (viewing) face of the chamber to align the target specimens for automated optical analysis. The small V-shaped grooves on the fluid side of the optically transparent (viewing) face of the chamber, and with the optimum dilution of magnetically-labeled specimens provides an alignment surface for automated optical analysis. Magnetically-labeled specimens and unbound magnetic particles move toward the inner surface of the chamber's viewing face, under the influence of the externally applied magnetic gradient. When they approach the surface, they come in contact with the slope of the V-shaped groove, forcing the magnetically-labeled specimens and unbound magnetic particles to move to the top of the groove.
U.S. Ser. No. 11/344,757 describe a device and method for automated collection and image anlaysis of detectably labeled rare target cells. These magnetically labeled rare cells are subjected to Time Delay Integration Imaging (TDI) in the CellTracks Platform. However when assessing circulating tumor cells (CTC) in the blood of cancer patients in order to correlate with disease activity, unbound magnetic particles that are left over from immunomagnetic separation will distort the image and interfere with confirmation of a captured target as a CTC.
The present invention provides a small groove design that allows for complete removal of the unbound magnetic particles in the analysis of labeled rare cells using TDI in the CellTracks platform.